Herpes simplex virus type 2 infections of the central nervous system: A retrospective study of 49 patients.

Herpes simplex virus type 2 (HSV-2) infections of the central nervous system (CNS) are rare with meningitis as the most common clinical presentation. We have investigated the clinical spectrum of CNS infections in 49 adult consecutive patients with HSV-2 genome in the cerebrospinal fluid (CSF). HSV-2 in the CSF was determined by polymerase chain reaction (PCR), and patients were diagnosed as encephalitis or meningitis according to predefined clinical criteria by retrospective data information from consecutive clinical journals. The annual crude incidence rate of HSV-2 CNS disease was 0.26 per 100,000. 43 (88%) had meningitis of whom 8 (19%) had recurring lymphocytic meningitis. Six patients (12%) had encephalitis. 11 of 49 patients (22%) had sequelae recorded during follow-up. None died as a result of HSV-2 CNS disease. Thus, the clinical presentation of HSV-2 infection of the CNS is mainly meningitis but encephalitis does occur and neurological sequelae are common. Recurring lymphocytic meningitis is associated with reactivation of HSV-2 and the condition might be underdiagnosed.